1. Field of the Invention
This invention relates generally to the field of coal gasification and, more specifically, to apparatus for feeding coal into a reactor of a high pressure coal gasifier.
2. Background of the Prior Art
Efforts are being made to find substitutes for natural gas which has become in short supply and more costly. It has been proposed to produce gas from coal. One commercially available process involves the partial oxidation of coal entrained in steam and oxygen to form carbon monoxide and hydrogen, both of which are combustible gases.
In this process of coal gasification the entrainment is fed through a burner into a hollow chamber where the entrainment reacts exothermically at a high temperature in a flame-like reaction to produce gas consisting primarily of carbon monoxide and hydrogen which exits from the top of the reactor. At the elevated temperature at which this reaction occurs, slagging conditions prevail and the ash, as a molten fluid, exits from the bottom of the reactor. The gas is sent to other operations for further processing, and the molten ash falls into a hopper of water where the ash is quenched, solidified, and removed as a solid.
Heretofore, it has been customary to use a screw conveyor either to feed the finely ground coal to the reactor where it reacts with the blast of steam and oxygen, or to feed the coal, oxygen and steam as a mixture to the reactor. Typical feed means in accordance with the prior art are shown in Zellerhoff et al., U.S. Pat. No. 3,036,906, "Apparatus for Gasification of Finely-Divided Fuels", issued May 29, 1962; and Klapp, U.S. Pat. No. 3,104,020, "Apparatus for Gasification of Finely-Divided Solid Fuels", issued Sept. 17, 1963.
Recently, experimental efforts have indicated that the pressurization of the reactor significantly increases the efficiency of this type of gasification process. However, the pressurization of the reactor causes a problem in feeding the feedstock, or coal, into the reactor. Back pressure from the pressurized reactor creates a neutralizing turbulance to the flow of coal which is merely entrained in a stream of steam and oxygen. Thus, the coal particles tend to separate out of the integrated mixture and efficiency of the process drops. Means are required to counteract this phenomena such that a completely mixed and integrated flow of the correct proportions of steam, oxygen and coal can be introduced and evenly distributed, as such, within the pressurized reactor.